[_paralyzed_]

you only need space to play low frequencies, no radio music has or any store bought cd's (except for bass specific cd's) play low enough to warrant that large of a room, however, a bigger woofer has a larger cone area and will play louder than a smaller woofer, he says he wants more bass than a single 12" with 285w gives him, so a smaller woofer is not the answer. A subwoofer is just a fancy air pump, move more air=more bass bigger woofer=more air moved. A plate amp is just an extra amp to only power the subwoofer. You'd still need a non-powered (passive) subwoofer. It's easier and cheaper to buy a powered subwoofer rather than an amp and a subwoofer.